The instant invention relates to aluminum titanate-based ceramic articles for use in high temperature applications. Specifically the invention relates to aluminum titanate-based ceramic articles having high permeability in combination with low thermal expansion and high thermal shock resistance, and being suitable for automotive emissions control.
In the industry cordierite (2MgO.2Al2O3.5SiO2) has been the cost-effective material of choice for automotive emissions control applications, such diesel exhaust aftertreatment systems, due to its combination of good thermal shock resistance, filtration efficiency, and durability under most operating conditions. However, under certain circumstances cordierite filters are susceptible to damage and have even catastrophically failed. Occasional thermal runaway occurs during uncontrolled regenerations resulting in localized cordierite melting.
Another factor contributing to cordierite failure occurs when metal impurities from the engine oil, catalytic additives or corroded metal from the exhaust port liners are introduced into the filter during operation. Typically, at temperatures exceeding 1300° C., these metals form oxides which react with the cordierite structure. Evidence of the failed material are usually small holes on the filter where the metal initially deposits and reacts causing corrosion and melting of the material.
Recently, silicon carbide (SiC) wall-flow filters have been made commercially available for diesel exhaust filtration. However, SiC filters are costly to manufacture, and must be segmented due to an inherent high coefficient of thermal expansion (CTE) and poor thermal shock resistance.
A need therefore exists for a ceramic article suitable for high temperature applications, such as automotive emissions control systems without the shortfalls of currently existing materials. The present invention provides such a ceramic material, and a method of making and using the same.